Publish/Subscribe API for Cocoa Objective-C SDK

Publish​

The publish function is used to send a message to all subscribers of a channel. To publish a message you must first specify a valid publishKey at initialization. A successfully published message is replicated across the PubNub Real-Time Network and sent simultaneously to all subscribed clients on a channel.

Messages in transit can be secured from potential eavesdroppers with SSL/TLS by setting ssl to true during initialization.

Publish Anytime​

It's not required to be subscribed to a channel in order to publish to that channel.

Message Data​

The message argument can contain any JSON serializable data, including: Objects, Arrays, Ints and Strings. data should not contain special Cocoa classes or functions as these will not serialize. String content can include any single-byte or multi-byte UTF-8 character.

Don't JSON serialize

It is important to note that you should not JSON serialize when sending signals/messages via PUBNUB. Why? Because the serialization is done for you automatically. Instead just pass the full object as the message payload. PubNub takes care of everything for you.

Message Size​

The maximum number of characters per message is 32 KiB by default. The maximum message size is based on the final escaped character count, including the channel name. An ideal message size is under 1800 bytes which allows a message to be compressed and sent using single IP datagram (1.5 KiB) providing optimal network performance.

If the message you publish exceeds the configured size, you will receive the following message:

Message Too Large Error​

["PUBLISHED",[0,"Message Too Large","13524237335750949"]]

For further details, check Calculating Message Payload Size Before Publish.

Message Publish Rate​

Messages can be published as fast as bandwidth conditions will allow. There is a soft limit based on max throughput since messages will be discarded if the subscriber can't keep pace with the publisher.

For example, if 200 messages are published simultaneously before a subscriber has had a chance to receive any messages, the subscriber may not receive the first 100 messages because the message queue has a limit of only 100 messages stored in memory.

Publishing to Multiple Channels​

It is not possible to publish a message to multiple channels simultaneously. The message must be published to one channel at a time.

Publishing Messages Reliably​

There are some best practices to ensure messages are delivered when publishing to a channel:

  • Publish to any given channel in a serial manner (not concurrently).
  • Check that the return code is success (for example, [1,"Sent","136074940..."])
  • Publish the next message only after receiving a success return code.
  • If a failure code is returned ([0,"blah","<timetoken>"]), retry the publish.
  • Avoid exceeding the in-memory queue's capacity of 100 messages. An overflow situation (aka missed messages) can occur if slow subscribers fail to keep up with the publish pace in a given period of time.
  • Throttle publish bursts in accordance with your app's latency needs, for example, Publish no faster than 5 msgs per second to any one channel.

Publishing Compressed Messages​

Message compression lets you send the message payload as the compressed body of an HTTP POST call.

Every PubNub SDK supports sending messages using the publish() call in one or more of the following ways:

  • Uncompressed, using HTTP GET (message sent in the URI)
  • Uncompressed, using HTTP POST (message sent in the body)
  • Compressed, using HTTP POST (compressed message sent in the body)

This section outlines what compressing a message means, and how to use compressed messages to your advantage.

Suppport for compressed messages

Currently, the C and Objective-C SDKs support compressed messages.

Message compression can be helpful if you want to send data exceeding the default 32 KiB message size limit, or use bandwidth more efficiently. Compressing messages is useful for scenarios that include high channel occupancy and quick exchange of information like ride hailing apps or multiplayer games.

Compression Trade-offs​

Small messages can expand​

Compressed messages generally have a smaller size, and can be delivered faster, but only if the original message is over 1 KiB. If you compress a signal (whose size is limited to 64 bytes), the compressed payload exceeds the signal's initial uncompressed size.

CPU overhead can increase​

While a smaller payload size is an advantage, working with compressed messages uses more CPU time than working with uncompressed messages. CPU time is required to compress the message on the sending client, and again to decompress the message on the receiving client. Efficient resource management is especially important on mobile devices, where increased usage affects battery life. Carefully consider the balance of lower bandwidth and higher speed versus any increased CPU usage.

Using Compression​

Compression methods and support vary between SDKs. If the receiving SDK doesn't support the sender's compression method, or even if it doesn't support compression at all, the PubNub server automatically changes the compressed message's format so that it is understandable to the recipient. No action is necessary from you.

Messages are not compressed by default; you must always explicitly specify that you want to use message compression. Refer to the code below for an example of sending a compressed message.

[self.client publish:@{@"message": @"This message will be compressed"}
           toChannel:@"channel_name" compressed:YES
      withCompletion:^(PNPublishStatus *status) {
    if (!status.isError) {
        // Message successfully published to specified channel.
    } else {
        // Handle error.
    }
}]

Method(s)​

To Publish a message you can use the following method(s) in the Cocoa SDK:

Publish a message with block​

- (void)publish:(id)message
         toChannel:(NSString *)channel
    withCompletion:(nullable PNPublishCompletionBlock)block;
* required
ParameterDescription
message *
Type: id
Reference on Foundation object ( NSString, NSNumber, NSArray, NSDictionary) which will be published.
channel *
Type: NSString
Reference on name of the channel to which message should be published.
block
Type: PNPublishCompletionBlock
Publish processing completion block which pass only one argument - request processing status to report about how data pushing was successful or not.

Publish a message with compression and block​

- (void)publish:(id)message
         toChannel:(NSString *)channel
        compressed:(BOOL)compressed
    withCompletion:(nullable PNPublishCompletionBlock)block;
* required
ParameterDescription
message *
Type: id
Reference on Foundation object (NSString, NSNumber, NSArray, NSDictionary) which will be published.
channel *
Type: NSString
Reference on name of the channel to which message should be published.
compressed *
Type: BOOL
Whether message should be compressed and sent with request body instead of URI part. Compression useful in case if large data should be published, in another case it will lead to packet size grow.
block
Type: PNPublishCompletionBlock
Publish processing completion block which pass only one argument - request processing status to report about how data pushing was successful or not.

Publish a message with storage and block​

- (void)publish:(id)message
         toChannel:(NSString *)channel
    storeInHistory:(BOOL)shouldStore
    withCompletion:(nullable PNPublishCompletionBlock)block;
* required
ParameterDescription
message *
Type: id
Reference on Foundation object (NSString, NSNumber, NSArray,NSDictionary) which will be published.
channel *
Type: NSString
Reference on name of the channel to which message should be published.
shouldStore *
Type: BOOL
With NO this message later won't be fetched using Message Persistence API.
block
Type: PNPublishCompletionBlock
Publish processing completion block which pass only one argument - request processing status to report about how data pushing was successful or not.

Publish a message with storage, compression, and block​

- (void)publish:(id)message
         toChannel:(NSString *)channel
    storeInHistory:(BOOL)shouldStore
        compressed:(BOOL)compressed
    withCompletion:(nullable PNPublishCompletionBlock)block;
* required
ParameterDescription
message *
Type: id
Reference on Foundation object (NSString, NSNumber, NSArray,NSDictionary) which will be published.
channel *
Type: NSString
Reference on name of the channel to which message should be published.
shouldStore *
Type: BOOL
With NO this message later won't be fetched using Message Persistence API.
compressed *
Type: BOOL
Compression useful in case if large data should be published, in another case it will lead to packet size grow.
block
Type: PNPublishCompletionBlock
Publish processing completion block which pass only one argument - request processing status to report about how data pushing was successful or not.

Publish a message with payload and block​

- (void)publish:(nullable id)message
            toChannel:(NSString *)channel
    mobilePushPayload:(nullable NSDictionary<NSString *, id> *)payloads
       withCompletion:(nullable PNPublishCompletionBlock)block;
* required
ParameterDescription
message
Type: id
Reference on Foundation object (NSString, NSNumber, NSArray, NSDictionary) which will be published.
channel *
Type: NSString
Reference on name of the channel to which message should be published.
payloads
Type: NSDictionary
Dictionary with payloads for different vendors (Apple with apns key and Google with gcm).
block
Type: PNPublishCompletionBlock
Publish processing completion block which pass only one argument - request processing status to report about how data pushing was successful or not.

Publish a message with payload, compression, and block​

- (void)publish:(nullable id)message
            toChannel:(NSString *)channel
    mobilePushPayload:(nullable NSDictionary<NSString *, id> *)payloads
           compressed:(BOOL)compressed
       withCompletion:(nullable PNPublishCompletionBlock)block;
* required
ParameterDescription
message
Type: id
Reference on Foundation object (NSString, NSNumber, NSArray, NSDictionary) which will be published.
channel *
Type: NSString
Reference on name of the channel to which message should be published.
payloads *
Type: NSDictionary
Dictionary with payloads for different vendors (Apple with apns key and Google with gcm).
compressed *
Type: BOOL
Compression useful in case if large data should be published, in another case it will lead to packet size grow.
block
Type: PNPublishCompletionBlock
Publish processing completion block which pass only one argument - request processing status to report about how data pushing was successful or not.

Publish a message with payload, storage, and block​

- (void)publish:(nullable id)message
            toChannel:(NSString *)channel
    mobilePushPayload:(nullable NSDictionary<NSString *, id> *)payloads
       storeInHistory:(BOOL)shouldStore
       withCompletion:(nullable PNPublishCompletionBlock)block;
* required
ParameterDescription
message
Type: id
Reference on Foundation object (NSString, NSNumber, NSArray,NSDictionary) which will be published.
channel *
Type: NSString
Reference on name of the channel to which message should be published.
payloads
Type: NSDictionary
Dictionary with payloads for different vendors (Apple with apns key and Google with gcm).
shouldStore *
Type: BOOL
With NO this message later won't be fetched using Message Persistence API.
block
Type: PNPublishCompletionBlock
Publish processing completion block which pass only one argument - request processing status to report about how data pushing was successful or not.

Publish a message with payload, storage, compression, and block​

- (void)publish:(nullable id)message
            toChannel:(NSString *)channel
    mobilePushPayload:(nullable NSDictionary<NSString *, id> *)payloads
       storeInHistory:(BOOL)shouldStore
           compressed:(BOOL)compressed
       withCompletion:(nullable PNPublishCompletionBlock)block;
* required
ParameterDescription
message
Type: id
Reference on Foundation object (NSString, NSNumber, NSArray,NSDictionary) which will be published.
channel *
Type: NSString
Reference on name of the channel to which message should be published.
payloads
Type: NSDictionary
Dictionary with payloads for different vendors (Apple with "apns" key and Google with "gcm").
shouldStore *
Type: BOOL
With NO this message later won't be fetched using Message Persistence API.
compressed *
Type: BOOL
Compression useful in case if large data should be published, in another case it will lead to packet size grow.
block
Type: PNPublishCompletionBlock
Publish processing completion block which pass only one argument - request processing status to report about how data pushing was successful or not.

Publish a message with metadata and block​

- (void)publish:(id)message
       toChannel:(NSString *)channel
    withMetadata:(nullable NSDictionary<NSString *, id> *)metadata
      completion:(nullable PNPublishCompletionBlock)block;
* required
ParameterDescription
message *
Type: id
The message may be any valid foundation object (String, NSNumber, Array, Dictionary).
channel *
Type: NSString
Specifies channel name to publish messages to.
metadata
Type: NSDictionary
NSDictionary with values which should be used by PubNub service to filter messages.
block
Type: PNPublishCompletionBlock
The completion block which will be called when the processing is complete, has one argument: - request status reports the publish was successful or not (errorData contains error information in case of failure).

Publish a message with compression, metadata, and block​

- (void)publish:(id)message
       toChannel:(NSString *)channel
      compressed:(BOOL)compressed
    withMetadata:(nullable NSDictionary<NSString *, id> *)metadata
      completion:(nullable PNPublishCompletionBlock)block;
* required
ParameterDescription
message *
Type: id
The message may be any valid foundation object (String, NSNumber, Array, Dictionary).
channel *
Type: NSString
Specifies channel name to publish messages to.
compressed *
Type: BOOL
If true the message will be compressed and sent with request body instead of the URI. Compression useful in case of large data, in another cases it will increase the packet size.
metadata
Type: NSDictionary
NSDictionary with values which should be used by PubNub service to filter messages.
block
Type: PNPublishCompletionBlock
The completion block which will be called when the processing is complete, has one argument: - request status reports the publish was successful or not (errorData contains error information in case of failure).

Publish a message with storage, metadata, and block​

- (void)publish:(id)message
         toChannel:(NSString *)channel
    storeInHistory:(BOOL)shouldStore
      withMetadata:(nullable NSDictionary<NSString *, id> *)metadata
        completion:(nullable PNPublishCompletionBlock)block;
* required
ParameterDescription
message *
Type: id
The message may be any valid foundation object (String, NSNumber, Array, Dictionary).
channel *
Type: NSString
Specifies channel name to publish messages to.
shouldStore *
Type: BOOL
If false the messages will not be stored in Message Persistence, default true.
metadata
Type: NSDictionary
NSDictionary with values which should be used by PubNub service to filter messages.
block
Type: PNPublishCompletionBlock
The completion block which will be called when the processing is complete, has one argument: - request status reports the publish was successful or not (errorData contains error information in case of failure).

Publish a message with storage, compression, metadata, and block​

- (void)publish:(id)message
         toChannel:(NSString *)channel
    storeInHistory:(BOOL)shouldStore
        compressed:(BOOL)compressed
      withMetadata:(nullable NSDictionary<NSString *, id> *)metadata
        completion:(nullable PNPublishCompletionBlock)block;
* required
ParameterDescription
message *
Type: id
The message may be any valid foundation object (String, NSNumber, Array, Dictionary).
channel *
Type: NSString
Specifies channel name to publish messages to.
shouldStore *
Type: BOOL
If false the messages will not be stored in Message Persistence, default true.
compressed *
Type: BOOL
If true the message will be compressed and sent with request body instead of the URI. Compression useful in case of large data, in another cases it will increase the packet size.
metadata
Type: NSDictionary
NSDictionary with values which should be used by PubNub service to filter messages.
block
Type: PNPublishCompletionBlock
The completion block which will be called when the processing is complete, has one argument: - request status reports the publish was successful or not (errorData contains error information in case of failure).

Publish a message with payload, metadata, and block​

- (void)publish:(nullable id)message
            toChannel:(NSString *)channel
    mobilePushPayload:(nullable NSDictionary<NSString *, id> *)payloads
         withMetadata:(nullable NSDictionary<NSString *, id> *)metadata
           completion:(nullable PNPublishCompletionBlock)block;
* required
ParameterDescription
message
Type: id
The message may be any valid foundation object (String, NSNumber, Array, Dictionary).
channel *
Type: NSString
Specifies channel name to publish messages to.
payloads
Type: NSDictionary
Dictionary with payloads for different vendors (Apple with aps key and Google with gcm). Either payloads or message should be provided..
metadata
Type: NSDictionary
NSDictionary with values which should be used by PubNub service to filter messages.
block
Type: PNPublishCompletionBlock
The completion block which will be called when the processing is complete, has one argument: - request status reports the publish was successful or not (errorData contains error information in case of failure).

Publish a message with payload, compression, metadata, and block​

- (void)publish:(nullable id)message
            toChannel:(NSString *)channel
    mobilePushPayload:(nullable NSDictionary<NSString *, id> *)payloads
           compressed:(BOOL)compressed
         withMetadata:(nullable NSDictionary<NSString *, id> *)metadata
           completion:(nullable PNPublishCompletionBlock)block;
* required
ParameterDescription
message
Type: id
The message may be any valid foundation object (String, NSNumber, Array, Dictionary).
channel *
Type: NSString
Specifies channel name to publish messages to.
payloads
Type: NSDictionary
Dictionary with payloads for different vendors (Apple with aps key and Google with gcm). Either payloads or message should be provided.
compressed *
Type: BOOL
If true the message will be compressed and sent with request body instead of the URI. Compression useful in case of large data, in another cases it will increase the packet size.
metadata
Type: NSDictionary
NSDictionary with values which should be used by PubNub service to filter messages.
block
Type: PNPublishCompletionBlock
The completion block which will be called when the processing is complete, has one argument: - request status reports the publish was successful or not (errorData contains error information in case of failure).

Publish a message with payload, storage, metadata, and block​

- (void)publish:(nullable id)message
            toChannel:(NSString *)channel
    mobilePushPayload:(nullable NSDictionary<NSString *, id> *)payloads
       storeInHistory:(BOOL)shouldStore
         withMetadata:(nullable NSDictionary<NSString *, id> *)metadata
           completion:(nullable PNPublishCompletionBlock)block;
* required
ParameterDescription
message
Type: id
The message may be any valid foundation object (String, NSNumber, Array, Dictionary).
channel *
Type: NSString
Specifies channel name to publish messages to.
payloads
Type: NSDictionary
Dictionary with payloads for different vendors (Apple with a ps key and Google with gcm). Either payloads or message should be provided.
shouldStore *
Type: BOOL
If false the messages will not be stored in Message Persistence, default true.
metadata
Type: NSDictionary
NSDictionary with values which should be used by PubNub service to filter messages.
block
Type: PNPublishCompletionBlock
The completion block which will be called when the processing is complete, has one argument: - request status reports the publish was successful or not (errorData contains error information in case of failure).

Publish a message with payload, storage, compression, metadata, and block​

- (void)publish:(nullable id)message
            toChannel:(NSString *)channel
    mobilePushPayload:(nullable NSDictionary<NSString *, id> *)payloads
       storeInHistory:(BOOL)shouldStore
           compressed:(BOOL)compressed
         withMetadata:(nullable NSDictionary<NSString *, id> *)metadata
           completion:(nullable PNPublishCompletionBlock)block;
* required
ParameterDescription
message
Type: id
The message may be any valid foundation object (String, NSNumber, Array, Dictionary).
channel *
Type: NSString
Specifies channel name to publish messages to.
payloads
Type: NSDictionary
Dictionary with payloads for different vendors (Apple with aps key and Google with gcm). Either payloads or message should be provided.
shouldStore *
Type: BOOL
If false the messages will not be stored in Message Persistence, default true.
compressed *
Type: BOOL
If true the message will be compressed and sent with request body instead of the URI. Compression useful in case of large data, in another cases it will increase the packet size.
metadata
Type: NSDictionary
NSDictionary with values which should be used by PubNub service to filter messages.
block
Type: PNPublishCompletionBlock
The completion block which will be called when the processing is complete, has one argument: - request status reports the publish was successful or not (errorData contains error information in case of failure).

Basic Usage​

Publish a message to a channel​

[self.client publish: @{@"Dictionary": @[@"with",@"array",@"as", @"value"]}
           toChannel: @"pubnub" withCompletion:^(PNPublishStatus *status) {

    if (!status.isError) {

        // Message successfully published to specified channel.
    }
    else {

        /**
         Handle message publish error. Check 'category' property to find
         out possible reason because of which request did fail.
         Review 'errorData' property (which has PNErrorData data type) of status
         object to get additional information about issue.

show all 19 lines
Subscribe to the channel

Before running the above publish example, either using the Debug Console or in a separate script running in a separate terminal window, subscribe to the same channel that is being published to.

Response​

Response objects which is returned by client when publish API is used:

@interface PNPublishData : PNServiceData

@property (nonatomic, readonly, strong) NSNumber *timetoken;
@property (nonatomic, readonly, strong) NSString *information;

@end

@interface PNPublishStatus : PNAcknowledgmentStatus

@property (nonatomic, readonly, strong) PNPublishData *data;

@end

Other Examples​

Publish with metadata​

[self publish: @"Hello from the PubNub Objective-C" toChannel:@"chat_channel"
    withMetadata: @{@"senderID" : @"bob"}  completion:^(PNPublishStatus *status) {

    if (!status.isError) {

        // Message successfully published to specified channel.
    }
    else {

        /**
            Handle message publish error. Check 'category' property to find
            out possible reason because of which request did fail.
            Review 'errorData' property (which has PNErrorData data type) of status
            object to get additional information about issue.

show all 19 lines

Push Payload Helper​

You can use the helper method as an input to the Message parameter, to format the payload for publishing Push messages. For more info on the helper method, check Create Push Payload Helper Section

Publish (Builder Pattern)​

This function publishes a message on a channel.

Optional arguments

This method uses the builder pattern, you can remove the args which are optional.

Method(s)​

To run Publish Builder you can use the following method(s) in the Cocoa SDK:

publish()
    .message(id)
    .channel(NSString *)
    .shouldStore(BOOL)
    .compress(BOOL)
    .ttl(NSUInteger)
    .payloads(NSDictionary *)
    .metadata(NSDictionary *)
    .performWithCompletion(nullable PNPublishCompletionBlock);
* required
ParameterDescription
message
Type: id
The message may be any valid foundation object (NSString, NSNumber, NSArray, NSDictionary).
channel *
Type: NSString
Specifies channel name to publish messages to.
shouldStore
Type: BOOL
If NO the messages will not be stored in history.
Default YES.
compress
Type: BOOL
If YES the message will be compressed and sent with request body instead of the URI. Compression useful in case of large data, in another cases it will increase the packet size.
ttl
Type: NSUInteger
Specify for how many hours published message should be stored.
payloads
Type: NSDictionary
Dictionary with payloads for different vendors (Apple with aps key and Google with gcm). Either payloads or message should be provided.
metadata
Type: NSDictionary
NSDictionary with values which should be used by PubNub service to filter messages.
block
Type: PNPublishCompletionBlock
The completion block which will be called when the processing is complete, has one argument: - request status reports the publish was successful or not (errorData contains error information in case of failure).

Basic Usage​

Publish message which will be stored in channel's Message Persistence for next 16 hours.

self.client.publish().channel(@"my_channel").message(@"Hello from PubNub iOS!").shouldStore(YES).ttl(16).performWithCompletion(^(PNPublishStatus *status) {

    if (!status.isError) {

        // Message successfully published to specified channel.
    }
    else {

        /**
         Handle message publish error. Check 'category' property to find
         out possible reason because of which request did fail.
         Review 'errorData' property (which has PNErrorData data type) of status
         object to get additional information about issue.

         Request can be resent using: [status retry];
show all 18 lines

Fire (Builder Pattern)​

The fire endpoint allows the client to send a message to BLOCKS Event Handlers. These messages will go directly to any Event Handlers registered on the channel that you fire to and will trigger their execution. The content of the fired request will be available for processing within the Event Handler. The message sent via fire() is not replicated, and so will not be received by any subscribers to the channel. The message is also not stored in history.

Optional arguments

This method uses the builder pattern, you can remove the args which are optional.

Method(s)​

To Fire a message you can use the following method(s) in the Cocoa SDK:

fire()
    .message(id)
    .channel(NSString *)
    .compress(BOOL)
    .payloads(NSDictionary *)
    .metadata(NSDictionary *)
    .performWithCompletion(nullable PNPublishCompletionBlock);
* required
ParameterDescription
message
Type: id
The message may be any valid foundation object (NSString, NSNumber, NSArray, NSDictionary).
channel *
Type: NSString
Specifies channel name to publish messages to.
compress
Type: BOOL
If YES the message will be compressed and sent with request body instead of the URI. Compression useful in case of large data, in another cases it will increase the packet size.
payloads
Type: NSDictionary
Dictionary with payloads for different vendors (Apple with aps key and Google with gcm). Either payloads or message should be provided.
metadata
Type: NSDictionary
NSDictionary with values which should be used by PubNub service to filter messages.
block
Type: PNPublishCompletionBlock
The completion block which will be called when the processing is complete, has one argument: - request status reports the publish was successful or not (errorData contains error information in case of failure).

Basic Usage​

self.client.fire()
    .channel(@"my_channel")
    .message(@"Hello from PubNub iOS!")
    .shouldStore(YES)
    .performWithCompletion(^(PNPublishStatus *status) {

    if (!status.isError) {

        // Message successfully published to specified channel.
    }
    else {

        /**
         Handle message publish error. Check 'category' property to find
         out possible reason because of which request did fail.
show all 22 lines

Signal​

The signal() function is used to send a signal to all subscribers of a channel.

By default, signals are limited to a message payload size of 64 bytes. This limit applies only to the payload, and not to the URI or headers. If you require a larger payload size, please contact support.

Method(s)​

To Signal a message you can use the following method(s) in the Cocoa SDK:

- (void)signal:(id)message
           channel:(NSString *)channel
    withCompletion:(nullable PNSignalCompletionBlock)block;
* required
ParameterDescription
message *
Type: id
Object (NSString, NSNumber, NSArray, NSDictionary) which will be sent with signal.
channel *
Type: NSString
Name of the channel to which signal should be sent.
block
Type: PNSignalCompletionBlock
Signal processing completion block which pass only one argument - request processing status to report about how data pushing was successful or not.

Basic Usage​

Signal a message to a channel​

[self.client signal:@{ @"Hello": @"world" } channel:@"announcement"
     withCompletion:^(PNSignalStatus *status) {

    if (!status.isError) {
        // Signal successfully sent to specified channel.
    } else {
        /**
         * Handle signal sending error. Check 'category' property to find out possible issue
         * because of which request did fail.
         *
         * Request can be resent using: [status retry];
         */
    }
}];

Response​

Response objects returned by the client when Signal API is used:

@interface PNSignalStatusData : PNServiceData

@property (nonatomic, readonly, strong) NSNumber *timetoken;
@property (nonatomic, readonly, strong) NSString *information;

@end

@interface PNSignalStatus : PNAcknowledgmentStatus

@property (nonatomic, readonly, strong) PNSignalStatusData *data;

@end

Signal (Builder Pattern)​

Optional arguments

This method uses the builder pattern, you can remove the args which are optional.

Method(s)​

To run Signal Builder you can use the following method(s) in the Cocoa SDK:

signal()
    .message(id)
    .channel(NSString *)
    .performWithCompletion(nullable PNSignalCompletionBlock);
* required
ParameterDescription
message *
Type: Array
Object (NSString, NSNumber, NSArray, NSDictionary) which will be sent with signal.
channel *
Type: String
Name of the channel to which signal should be sent.
block
Type: PNSignalCompletionBlock
Signal processing completion block which pass only one argument - request processing status to report about how data pushing was successful or not.

Basic Usage​

Signal a message to a channel​

self.client.signal()
    .message(@{ @"Hello": @"world" }).channel(@"announcement")
    .performWithCompletion(^(PNSignalStatus *status) {

    if (!status.isError) {
        // Signal successfully sent to specified channel.
    } else {
        /**
         * Handle signal sending error. Check 'category' property to find out possible issue
         * because of which request did fail.
         *
         * Request can be resent using: [status retry];
         */
    }
});

Response​

Response objects which is returned by client when Signal API is used::

@interface PNSignalStatusData : PNServiceData

@property (nonatomic, readonly, strong) NSNumber *timetoken;
@property (nonatomic, readonly, strong) NSString *information;

@end

@interface PNSignalStatus : PNAcknowledgmentStatus

@property (nonatomic, readonly, strong) PNSignalStatusData *data;

@end

Subscribe​

This function causes the client to create an open TCP socket to the PubNub Real-Time Network and begin listening for messages on a specified channel. To subscribe to a channel the client must send the appropriate subscribeKey at initialization. By default a newly subscribed client will only receive messages published to the channel after the subscribeToChannels call completes.

Connectivity notification

You can be notified of connectivity via the connect callback. By waiting for the connect callback to return before attempting to publish, you can avoid a potential race condition on clients that subscribe and immediately publish messages before the subscribe has completed.

Using Cocoa SDK, if a client becomes disconnected from a channel, it can automatically attempt to reconnect to that channel and retrieve any available messages that were missed during that period by setting restore to YES. By default a client will attempt to reconnect after exceeding a 320 second connection timeout.

Unsubscribing from all channels

Unsubscribing from all channels, and then subscribing to a new channel Y is not the same as subscribing to channel Y and then unsubscribing from the previously-subscribed channel(s). Unsubscribing from all channels resets the last-received timetoken and thus, there could be some gaps in the subscription that may lead to message loss.

Method(s)​

To Subscribe to a channel you can use the following method(s) in the Cocoa SDK:

Subscribe to channels with presence​

- (void)subscribeToChannels:(NSArray<NSString *> *)channels
               withPresence:(BOOL)shouldObservePresence;
* required
ParameterDescription
channels *
Type: NSArray
List of channel names on which client should try to subscribe.
shouldObservePresence *
Type: BOOL
Whether presence observation should be enabled for channels or not.

Subscribe to channels with presence and state​

- (void)subscribeToChannels:(NSArray<NSString *> *)channels
               withPresence:(BOOL)shouldObservePresence
                clientState:(nullable NSDictionary<NSString *, id> *)state;
* required
ParameterDescription
channels *
Type: NSArray
List of channel names on which client should try to subscribe.
shouldObservePresence *
Type: BOOL
Whether presence observation should be enabled for channels or not.
state
Type: NSDictionary
Reference on dictionary which stores key-value pairs based on channel name and value which should be assigned to it.

Subscribe to channels with presence and timetoken​

- (void)subscribeToChannels:(NSArray<NSString *> *)channels
               withPresence:(BOOL)shouldObservePresence
             usingTimeToken:(nullable NSNumber *)timeToken;
* required
ParameterDescription
channels *
Type: NSArray
List of channel names on which client should try to subscribe.
shouldObservePresence *
Type: BOOL
Whether presence observation should be enabled for channels or not.
timeToken
Type: NSNumber
Specifies time from which to start returning any available cached messages. Message retrieval with timetoken is not guaranteed and should only be considered a best-effort service.

Subscribe to channels with presence, timetoken, and state​

- (void)subscribeToChannels:(NSArray<NSString *> *)channels
               withPresence:(BOOL)shouldObservePresence
             usingTimeToken:(nullable NSNumber *)timeToken
                clientState:(nullable NSDictionary<NSString *, id> *)state;
* required
ParameterDescription
channels *
Type: NSArray
List of channel names on which client should try to subscribe.
shouldObservePresence *
Type: BOOL
Whether presence observation should be enabled for channels or not.
timeToken
Type: NSNumber
Specifies time from which to start returning any available cached messages. Message retrieval with timetoken is not guaranteed and should only be considered a best-effort service.
state
Type: NSDictionary
Reference on dictionary which stores key-value pairs based on channel name and value which should be assigned to it.

Basic Usage​

Subscribe to a channel:

/**
 Subscription results arrive to a listener which should implement the
 PNObjectEventListener protocol and be registered as follows:
 */
[self.client addListener:self];
[self.client subscribeToChannels: @[@"my_channel1", @"my_channel2"] withPresence:NO];

// Handle a new message from a subscribed channel
- (void)client:(PubNub *)client didReceiveMessage:(PNMessageResult *)message {
    // Reference to the channel group containing the chat the message was sent to
    NSString *subscription = message.data.subscription;
    NSLog(@"%@ sent message to '%@' at %@: %@", message.data.publisher, message.data.channel,
            message.data.timetoken, message.data.message);
}

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Response​

@interface PNSubscriberData : PNServiceData

// Name of channel on which subscriber received data.
@property (nonatomic, readonly, strong) NSString *channel;

// Name of channel or channel group (if not equal to channel name).
@property (nonatomic, nullable, readonly, strong) NSString *subscription;

// Time at which the event arrived.
@property (nonatomic, readonly, strong) NSNumber *timetoken;

// Stores a reference to the metadata information passed along with the received event.
@property (nonatomic, nullable, readonly, strong) NSDictionary<NSString *, id> *userMetadata;

@end
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Other Examples​

Subscribing to a Presence channel​

Requires Presence

This method requires that the Presence add-on is enabled for your key in the Admin Portal.

For any given channel there is an associated Presence channel. You can subscribe directly to the channel by appending -pnpres to the channel name. For example the channel named my_channel would have the presence channel named my_channel-pnpres.

/**
    Subscription process results arrive to listener which should adopt to
    PNObjectEventListener protocol and registered using:
    */
[self.client addListener:self];
[self.client subscribeToPresenceChannels:@[@"my_channel"]];

// New presence event handling.
- (void)client:(PubNub *)client didReceivePresenceEvent:(PNPresenceEventResult *)event {

    if (![event.data.channel isEqualToString:event.data.subscription]) {

        // Presence event has been received on channel group stored in event.data.subscription.
    }
    else {
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Sample Responses​

Join Event​

{
    "action": "join",
    "timestamp": 1345546797,
    "uuid": "175c2c67-b2a9-470d-8f4b-1db94f90e39e",
    "occupancy": 2
}
Leave Event​
{
    "action" : "leave",
    "timestamp" : 1345549797,
    "uuid" : "175c2c67-b2a9-470d-8f4b-1db94f90e39e",
    "occupancy" : 1
}
Timeout Event​
{
    "action": "timeout",
    "timestamp": 1345549797,
    "uuid": "76c2c571-9a2b-d074-b4f8-e93e09f49bd",
    "occupancy": 0
}
State Change Event​
{
    "action": "state-change",
    "uuid": "76c2c571-9a2b-d074-b4f8-e93e09f49bd",
    "timestamp": 1345549797,
    "data": {
        "isTyping": true
    }
}
Interval Event​
{
    "action":"interval",
    "timestamp":1474396578,
    "occupancy":2
}

When a channel is in interval mode with presence_deltas pnconfig flag enabled, the interval message may also include the following fields which contain an array of changed UUIDs since the last interval message.

  • joined
  • left
  • timedout

For example, this interval message indicates there were 2 new UUIDs that joined and 1 timed out UUID since the last interval:

{
    "action" : "interval",
    "occupancy" : <# users in channel>,
    "timestamp" : <unix timestamp>,
    "joined" : ["uuid2", "uuid3"],
    "timedout" : ["uuid1"]
}

If the full interval message is greater than 30KB (since the max publish payload is ∼32KB), none of the extra fields will be present. Instead there will be a here_now_refresh boolean field set to true. This indicates to the user that they should do a hereNow request to get the complete list of users present in the channel.

{
    "action" : "interval",
    "occupancy" : <# users in channel>,
    "timestamp" : <unix timestamp>,
    "here_now_refresh" : true
}

Wildcard subscribe to channels​

Requires Stream Controller add-on

This method requires that the Stream Controller add-on is enabled for your key in the Admin Portal (with Enable Wildcard Subscribe checked). Read the support page on enabling add-on features on your keys.

Wildcard subscribes allow the client to subscribe to multiple channels using wildcard. For example, if you subscribe to a.* you will get all messages for a.b, a.c, a.x. The wildcarded * portion refers to any portion of the channel string name after the dot (.).

[self.client subscribeToChannels: @[@"my_channel.*"] withPresence:YES];
Wildcard grants and revokes

Only one level (a.*) of wildcarding is supported. If you grant on * or a.b.*, the grant will treat * or a.b.* as a single channel named either * or a.b.*. You can also revoke permissions from multiple channels using wildcards but only if you previously granted permissions using the same wildcards. Wildcard revokes, similarly to grants, only work one level deep, like a.*.

Subscribing with State​

This method requires that the Presence add-on is enabled for your key in the Admin Portal. Read the support page on enabling add-on features on your keys. :::

Required UUID

Always set the UUID to uniquely identify the user or device that connects to PubNub. This UUID should be persisted, and should remain unchanged for the lifetime of the user or the device. If you don't set the UUID, you won't be able to connect to PubNub.

// Initialize and configure PubNub client instance
PNConfiguration *configuration = [PNConfiguration configurationWithPublishKey:@"demo" subscribeKey:@"demo"];
configuration.uuid = @"myUniqueUUID";
self.client = [PubNub clientWithConfiguration:configuration];
[self.client addListener:self];

// Subscribe to demo channel with presence observation
[self.client subscribeToChannels: @[@"my_channel"] withPresence:YES];

- (void)client:(PubNub *)client didReceiveStatus:(PNStatus *)status {

    if (status.category == PNConnectedCategory) {
        [self.client setState: @{@"new": @"state"} forUUID:self.client.uuid onChannel: @"my_channel"
                withCompletion:^(PNClientStateUpdateStatus *status) {

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Subscribe Channel Group​

Requires Stream Controller add-on

This method requires that the Stream Controller add-on is enabled for your key in the Admin Portal. Read the support page on enabling add-on features on your keys.

This functions subscribes to a channel group.

Method(s)​

To Subscribe to a Channel Group you can use the following method(s) in the Cocoa SDK:

Subscribe to channel groups with presence​

- (void)subscribeToChannelGroups:(NSArray<NSString *> *)groups
                    withPresence:(BOOL)shouldObservePresence;
* required
ParameterDescription
groups *
Type: NSArray
List of channel group names on which client should try to subscribe.
shouldObservePresence *
Type: BOOL
Whether presence observation should be enabled for groups or not.

Subscribe to channel groups with state​

- (void)subscribeToChannelGroups:(NSArray<NSString *> *)groups
                    withPresence:(BOOL)shouldObservePresence
                     clientState:(nullable NSDictionary<NSString *, id> *)state;
* required
ParameterDescription
groups *
Type: NSArray
List of channel group names on which client should try to subscribe.
shouldObservePresence *
Type: BOOL
Whether presence observation should be enabled for groups or not.
state
Type: NSDictionary
Reference on dictionary which stores key-value pairs based on channel group name and value which should be assigned to it.

Basic Usage​

Subscribe to a channel group

NSString *channelGroup = @"family";
/**
 Subscription process results arrive to listener which should adopt to
 PNObjectEventListener protocol and registered using:
 */
[self.client addListener:self];
[self.client subscribeToChannelGroups:@[channelGroup] withPresence:NO];

// Handle new message from one of channels on which client has been subscribed.
- (void)client:(PubNub *)client didReceiveMessage:(PNMessageResult *)message {

    // Handle new message stored in message.data.message
    if (![message.data.channel isEqualToString:message.data.subscription]) {

        // Message has been received on channel group stored in message.data.subscription.
    }
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Response​

@interface PNSubscriberData : PNServiceData

// Name of channel for which subscriber received data.
@property (nonatomic, readonly, strong) NSString *channel;
// Name of channel or channel group (in case if not equal to channel).
@property (nonatomic, nullable, readonly, strong) NSString *subscription;
// Time at which event arrived.
@property (nonatomic, readonly, strong) NSNumber *timetoken;
// Stores reference on metadata information which has been passed along with received event.
@property (nonatomic, nullable, readonly, strong) NSDictionary<NSString *, id> *userMetadata;

@end

@interface PNSubscribeStatus : PNErrorStatus

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Other Examples​

Subscribe to the presence channel of a channel group​

Requires Stream Controller and Presence add-ons

This method requires both the Stream Controller and Presence add-ons are enabled for your key in the Admin Portal. Read the support page on enabling add-on features on your keys.

/**
    Subscription process results arrive to listener which should adopt to
    PNObjectEventListener protocol and registered using:
    */
[self.client addListener:self];
[self.client subscribeToChannelGroups:@[channelGroup] withPresence:YES];

// Handle new message from one of channels on which client has been subscribed.
- (void)client:(PubNub *)client didReceiveMessage:(PNMessageResult *)message {

    // Handle new message stored in message.data.message
    if (![message.data.channel isEqualToString:message.data.subscription]) {

        // Message has been received on channel group stored in message.data.subscription.
    }
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Unsubscribe​

When subscribed to a single channel, this function causes the client to issue a leave from the channel and close any open socket to the PubNub Network. For multiplexed channels, the specified channel(s) will be removed and the socket remains open until there are no more channels remaining in the list.

Unsubscribing from all channels

Unsubscribing from all channels, and then subscribing to a new channel Y is not the same as subscribing to channel Y and then unsubscribing from the previously-subscribed channel(s). Unsubscribing from all channels resets the last-received timetoken and thus, there could be some gaps in the subscription that may lead to message loss.

Method(s)​

To Unsubscribe from a channel you can use the following method(s) in the Cocoa SDK:

- (void)unsubscribeFromChannels:(NSArray<NSString *> *)channels
                   withPresence:(BOOL)shouldObservePresence;
* required
ParameterDescription
channels *
Type: NSArray
List of channel names from which client should try to unsubscribe.
shouldObservePresence *
Type: BOOL
Whether client should disable presence observation on specified channels or keep listening for presence event on them.

Basic Usage​

Unsubscribe from a channel:

/**
 Unsubscription process results arrive to listener which should adopt to
 PNObjectEventListener protocol and registered using:
 */
[self.client addListener:self];
[self.client unsubscribeFromChannels: @[@"my_channel1", @"my_channel2"] withPresence:NO];

// Handle subscription status change.
- (void)client:(PubNub *)client didReceiveStatus:(PNStatus *)status {

    if (status.operation == PNUnsubscribeOperation && status.category == PNDisconnectedCategory) {

        /**
         This is the expected category for an unsubscribe. This means there was no error in
         unsubscribing from everything.
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Response​

@interface PNSubscriberData : PNServiceData

// Name of channel for which subscriber received data.
@property (nonatomic, readonly, strong) NSString *channel;
// Name of channel or channel group (in case if not equal to channel).
@property (nonatomic, nullable, readonly, strong) NSString *subscription;
// Time at which event arrived.
@property (nonatomic, readonly, strong) NSNumber *timetoken;
// Stores reference on metadata information which has been passed along with received event.
@property (nonatomic, nullable, readonly, strong) NSDictionary<NSString *, id> *userMetadata;

@end

@interface PNSubscribeStatus : PNErrorStatus

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Unsubscribe All​

Unsubscribe from all channels and all channel groups

Method(s)​

- (void)unsubscribeFromAll;

Basic Usage​

/**
 Unsubscription process results arrive to listener which should adopt to
 PNObjectEventListener protocol and registered using:
 */
[self.client addListener:self];
[self.client unsubscribeFromAll];

// Handle subscription status change.
- (void)client:(PubNub *)client didReceiveStatus:(PNStatus *)status {

    if (status.operation == PNUnsubscribeOperation && status.category == PNDisconnectedCategory) {

        /**
         This is the expected category for an unsubscribe. This means there was no error in unsubscribing
         from everything.
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Returns​

None

Unsubscribe from a Channel Group​

This function lets you Unsubscribe from a Channel Group

Method(s)​

To run Unsubscribe from a Channel Group you can use the following method(s) in the Cocoa SDK:

- (void)unsubscribeFromChannelGroups:(NSArray<NSString *> *)groups
                        withPresence:(BOOL)shouldObservePresence;
* required
ParameterDescription
groups *
Type: NSArray
List of channel group names from which client should try to unsubscribe.
shouldObservePresence *
Type: BOOL
Whether client should disable presence observation on specified channel groups or keep listening for presence event on them.

Basic Usage​

Unsubscribe from a Channel Group: 

/**
 Unsubscription process results arrive to listener which should adopt to
 PNObjectEventListener protocol and registered using:
 */
[self.client addListener:self];
[self.client unsubscribeFromChannelGroups: @[@"developers"] withPresence:YES];

// Handle subscription status change.
- (void)client:(PubNub *)client didReceiveStatus:(PNStatus *)status {

    if (status.operation == PNUnsubscribeOperation && status.category == PNDisconnectedCategory) {

        /**
         This is the expected category for an unsubscribe. This means there was no error in unsubscribing
         from everything.
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Response​

@interface PNSubscriberData : PNServiceData

// Name of channel for which subscriber received data.
@property (nonatomic, readonly, strong) NSString *channel;
// Name of channel or channel group (in case if not equal to channel).
@property (nonatomic, nullable, readonly, strong) NSString *subscription;
// Time at which event arrived.
@property (nonatomic, readonly, strong) NSNumber *timetoken;
// Stores reference on metadata information which has been passed along with received event.
@property (nonatomic, nullable, readonly, strong) NSDictionary<NSString *, id> *userMetadata;

@end

@interface PNSubscribeStatus : PNErrorStatus

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Presence​

This function is used to subscribe to the presence channel. Using Cocoa SDK, if a client becomes disconnected from a channel, it can automatically attempt to reconnect to that channel and retrieve any available messages that were missed during that period by setting restore to true. By default a client will attempt to reconnect after exceeding a 320 second connection timeout.

Method(s)​

To do Presence you can use the following method(s) in the Cocoa SDK:

- (void)subscribeToPresenceChannels:(NSArray<NSString *> *)channels;
* required
ParameterDescription
channels *
Type: NSArray
List of channel names for which client should try to subscribe on presence observing channels.

Basic Usage​

Subscribe to the presence channel: For any given channel there is an associated Presence channel. You can subscribe directly to the channel by appending -pnpres to the channel name. For example the channel named my_channel would have the presence channel named my_channel-pnpres

/**
 Subscription process results arrive to listener which should adopt to
 PNObjectEventListener protocol and registered using:
 */
[self.client addListener:self];
[self.client subscribeToPresenceChannels:@[@"my_channel"]];

// New presence event handling.
- (void)client:(PubNub *)client didReceivePresenceEvent:(PNPresenceEventResult *)event {

    if (![event.data.channel isEqualToString:event.data.subscription]) {

        // Presence event has been received on channel group stored in event.data.subscription.
    }
    else {
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Response​

@interface PNSubscriberData : PNServiceData

// Name of channel for which subscriber received data.
@property (nonatomic, readonly, strong) NSString *channel;
// Name of channel or channel group (in case if not equal to channel).
@property (nonatomic, nullable, readonly, strong) NSString *subscription;
// Time at which event arrived.
@property (nonatomic, readonly, strong) NSNumber *timetoken;
// Stores reference on metadata information which has been passed along with received event.
@property (nonatomic, nullable, readonly, strong) NSDictionary<NSString *, id> *userMetadata;

@end

@interface PNSubscribeStatus : PNErrorStatus

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Presence Unsubscribe​

This function lets you stop monitoring the presence of the channel(s). The channel(s) will be removed and the socket remains open until there are no more channels remaining in the list.

Method(s)​

To Unsubscribe from Presence of a channel you can use the following method(s) in the Cocoa SDK:

- (void)unsubscribeFromPresenceChannels:(NSArray<NSString *> *)channels;
* required
ParameterDescription
channels *
Type: NSArray
List of channel names for which client should try to unsubscribe from presence observing channels

Basic Usage​

Unsubscribe from the presence channel:

[self.client unsubscribeFromChannelGroups:@[@"developers"] withPresence:YES];

Response​

@interface PNSubscriberData : PNServiceData

// Name of channel for which subscriber received data.
@property (nonatomic, readonly, strong) NSString *channel;
// Name of channel or channel group (in case if not equal to channel).
@property (nonatomic, nullable, readonly, strong) NSString *subscription;
// Time at which event arrived.
@property (nonatomic, readonly, strong) NSNumber *timetoken;
// Stores reference on metadata information which has been passed along with received event.
@property (nonatomic, nullable, readonly, strong) NSDictionary<NSString *, id> *userMetadata;

@end

@interface PNSubscribeStatus : PNErrorStatus

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Listeners​

You can be notified of connectivity status, message and presence notifications via the listeners.

Listeners should be added before calling the method.

Add Listeners​

Listener's class should conform to PNEventsListener protocol to have access to available callbacks.

// Adding listener.
[pubnub addListener:self];

// Callbacks listed below.

- (void)client:(PubNub *)pubnub didReceiveMessage:(PNMessageResult *)message {
    NSString *channel = message.data.channel; // Channel on which the message has been published
    NSString *subscription = message.data.subscription; // Wild-card channel or channel on which PubNub client actually subscribed
    NSNumber *timetoken = message.data.timetoken; // Publish timetoken
    id msg = message.data.message; // Message payload
    NSString *publisher = message.data.publisher; // Message publisher
}

- (void)client:(PubNub *)pubnub didReceiveSignal:(PNSignalResult *)signal {
    NSString *channel = message.data.channel; // Channel on which the signal has been published
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Remove Listeners​

[pubnub removeListener:self]

Handling Disconnects​

SDK performs automated re-connections and call status handler to report back. This will happen forever, but user may decide to stop it.

- (void)client:(PubNub *)pubnub didReceiveStatus:(PNStatus *)status {
  if (status.isError && status.willAutomaticallyRetry) {
    // Stop automatic retry attempts.
    [status cancelAutomaticRetry];
  }
}

Listener status events​

CategoryDescription
PNAcknowledgmentCategory
An API call was successful. This status has additional details based on the type of the successful operation.
PNAccessDeniedCategory
Access Manager permission failure.
PNTimeoutCategory
Server didn't respond in time for reported operation request.
PNNetworkIssuesCategory
No connection to Internet.
PNRequestMessageCountExceededCategory
The SDK announces this error if requestMessageCountThreshold is set, and the number of messages received from PubNub (in-memory cache messages) exceeds the threshold.
PNConnectedCategory
The SDK subscribed to new channels / channel groups.
PNReconnectedCategory
The SDK was able to reconnect to PubNub.
PNDisconnectedCategory
The SDK unsubscribed from channels / channel groups.
PNUnexpectedDisconnectCategory
The SDK unexpectedly lost ability to receive live updated from PubNub.
PNRequestURITooLongCategory
Reported operation request URI too long (too many channels / channel groups).
PNMalformedFilterExpressionCategory
The SDK has been configured with malformed filtering expression.
PNMalformedResponseCategory
The SDK received unexpected PubNub service response.
PNDecryptionErrorCategory
The SDK unable to decrypt received message using configured cipherKey.
PNTLSConnectionFailedCategory
The SDK unable to establish secured connection.
PNTLSUntrustedCertificateCategory
The SDK unable to check certificates trust chain.
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